Conventional transmission control systems use a one way clutch or mechanical diode as an offgoing element to transfer torque through a powertrain. In these systems, release is controlled through a rate of an on-coming element during a shift. System compliant devices such as accumulators, wave plates, and orifices have been employed with line pressure control for shift feel to control the rate of the oncoming element. This system has physically prevented occurrence of tie-up or flare that cause undesired output torque disturbances. This system, however, is not suitable for use in a clutch to clutch transmission.
A clutch to clutch transmission reduces hardware cost and envelope size by removing the mechanical system compliant devices and diodes. An electronic control system controls the oncoming and offgoing elements precisely to avoid flare and tie-up.